Method of and device for exciting and regulating alternators



Dec. 6, 1960 I M LEROY 2,963,636

- METHOD OF AND DIVICE FOR EXCITING AND REGULATING ALTERNATORS Filed Aug. 5, 1957 2 Sheets-Sheet l lira/8W1? M,Ler o7 Dec. 6, 1960 M. LEROY 42,953,636

METHOD OF AND DEVICE FOR EXCITING AND REGULATING ALTERNATORS Filed Aug. 5, 1957 2 Sheets-Sheet 2 United States Patent O METHOD OF AND DEVICE FOR'EXCITING AND REGULATIN G ALTERNATORS Marcellin Leroy, 33 Rue Waldeck-Rousseau,

. Angouleme, France The invention relates to the regulation of alternate-rs by compounding which aims at the maintenance of constant voltage at the terminals, whatever may be the values of the load and of cos The problem of regulating the voltage at the field terminals, i.e. the strength of excitation current, in dependence on the output and the phase displacement of alternator current, has alreadyfound many solutions, notably those based on the use of two magnetic circuits which permit the introduction in the excitation circuit of a load-dependent and of a load-independent component respectively. But previously proposed solutions of this kind involve the use either of more or less complicated fittings which up to now had to be arranged outside the'machine, or of multiple collectors or slip rings.

The known solutions of this kind show the common feature of keeping the magnetic circuits separate and, with a view to the making up of the said components, of influencing the natural characteristics of the magnetic circuits in the generators which produce these components, the term generators being employed here in a very general sense where transformers represent only a particular case.

According to the present invention, in order to obtain the load-dependent and the load-independent components, rotary-field transformers are employed whose magnetic circuits and respective coils are adjustable in relation to one another, i.e. whose primary magnetic circuits-with their coils are adjustable in relation to one another and/or whose secondary magnetic circuits with their coils are adjustable in relation to one another, and are adjusted so as to alter the phase displacement of the excitation current.

Two rotary-field transformers are employed in a manner known per se, the primary of one being connected in shunt and the primary of the other being connected in series in regard to the circuit fed by the alternator, and the adjustment of the magnetic circuits is regulated, for a given value of cos e.g. cos =0.8, so as to reduce to a small value the phase displacement of the voltage supplied by the secondary of the second transformer, in relation to the voltage supplied for the purpose of no load excitation by the secondary of the first transformer.

Besides, the device according to the invention assures independence from a platform-regulation effected once and for all and permits of an easy adaptation of the regulation to the characteristics of the distribution network or to the employed type of alternator drive.

Although the concept of the invention includes static embodiments the invention offers considerable advantages if applied with rotary transformers.

The device according to the invention not only allows to achieve the regulation by very simple means but also to keep up or eliminate the conventional exciter and to fit instead the device according to the invention, a step which leads to the elimination of any collector device.

' another whose windings are connected in series.

2,963,636 Patented Dec. 6, 1960 Below are given exemplary embodiments of the inventive concept, the applicant not wishing however to limit the generic scope of his invention to the particulars, or by virtue of specific particulars, to the examples chosen for the purpose of illustration.

Fig. 1 shows the general assembly diagram.

Fig. 2 is a simplified diagram substantially analogous to the conventional Rothert diagram.

Fig. 3 shows an embodiment in which the secondaries are mounted on the pole wheel shaft, with stationary adjustable primary.

Fig. 4 shows a static solution.

Fig. 5 shows a modification with secondaries mounted on the pole wheel shaft and adjustable in relation to one another.

In Figs. 1 and 2 the alternator is designated by its armature 1 and its field 2 (Fig. 1). The system of excitation and regulation is constituted by two rotary transformers 3 and 4 with independent magnetic circuits.

The primary 4 of one transformer is connected in shunt with armature 1, and the primary 3 of the other transformer lies in the path of the output current.

According to the invention, both primaries are arranged to be adjustable in relation to one another.

The secondary 5 may be common to both transformers or may be constituted by two elements integral with one The current produced by this secondary is transmitted to the field 2 of the alternator by means of a rectifier 6. The excitation current is rectified by rectifier 6.

The primary 4 generates a voltage CA at the secondary terminals which corresponds to the no-load excitation.

The primary 3 produces a voltage AB proportional to the output current.

The resultant OB of OA and AB represents the voltage required for the excitation in load condition.

The direction of AB is obtained by the mutual adjustment of the two primaries which is chosen in such a way that the vector AB forms with the line OD a comparatively small angle a, i.e. so as to obtain unimportant variations of OB for a cos below a predetermined value, e.g. 0.8, and appreciable variations for any cos lying above the said value.

At constant output intensity, point B will vary between the position defined by a and the position C which corresponds to cos =1, and this position of point C regulation is achieved in a favourable region of the diagram as regards the variations of load as well as those of the operational cos Moreover it is obvious that by causing a variation of the angle a by very simple means the alternator can be over or undercompounded, and consequently the described arrangement may be regarded as an underor over-compounding device.

The device according to the invention permits of the elimination of the conventional exciter. Also, the transformer secondary or secondaries 5 as well as the rectifier 6 may be mounted on the pole wheel which eliminates any collector.

This modification is shown in Fig. 3 in which the secondaries 5 are mounted on the shaft of pole wheel 2 the same as rectifier 6, an arrangement which eliminates any collector. The primaries 3 and 4 are stationary.

The series primary 3 may be adjusted in the sense of the rotary field, or the shunted primary 4 may be adjusted in the opposite sense. It is equally feasible to adjust both primaries simultaneously in their respective senses.

In adjusting the shunted primary 4 by comparatively small angles with reference to the compounding position, in the rotary-field sense or in the opposite sense, thealternator becomes overor under-compounded;

In the static solutionshowninFig. 4 wherethesame annotations are employed as in Fig. 3, theassembly designated generally by 7 is stationary and separate from-the alternator; the terminals 8 of rectifier 6 are connected to the terminals 9 of the alternator which latter terminals may be connected either directly to the slip rings of the pole wheel or to the inductors of the exciter according to'whether the latter is kept or eliminated as previously indicated.

In the modification of Fig. the primaries3 and.4 are mounted so as to be stationary and the twosecondaries 5 and 50, mounted on the shaft of pole Wheel 2, lie in series but secondary 50 is mounted onthe shaft in such a Way as to be angularly adjustable in relation to secondary 5.

The above-mentioned embodiments are the simplest and the most practical. But other arrangements are possible which will yield the same results as regards the. vector diagram.

From amongst such other equivalent but less simple solutions the following instances may be mentioned:

To let the primaries rotate; but this will necessitate multiple. slip rings in order to apply the current.

It is also possible, in the case of rotating secondaries, to adjust the secondaries and to complete the regulation by adjusting one of the two primaries.

The device may equally well be applied to an alternator with rotary armature: in this case the secondary 5 is mounted on the stationary part while theprimaries 3 and 4 turn with the armature.

By way of a modified embodiment, the armature of the conventional exciter may be maintained and the device according to the invention may be applied to the inductors of the latter.

What I claim is:

1. In combination, an alternating current circuit, an alternator having an armature winding connected to said circuit and a field winding, an excitation circuit for said field Winding comprising a rectifier, a first rotary field transformer having a primary winding and a secondary Winding, said primary Winding connected in series in the said alternating current circuit, a second rotary field transformer having a primary winding and a secondary winding, the said primary Winding connected in parallel to the alternating current circuit, the secondaries ofthe said first and second transformers connected in series with said rectifier in said excitation circuit, and means to shift the windings of at leastone rotary field transformer relative to each other.

2. The combination as set forth in claim 1, in which the rotary-field transformers are of the rotary type.

3. The combination as set forth in claim 2, inwhich the secondaries of both transformers are mounted. on a common rotating shaft, the primaries of the transformers being stationary.

4. The combination as set forth in claim 3, comprising means to adjust the angular position of the secondaries relatively one to the other.

.5. The combination as set forth in claim 3, comprising means to. adjust the angular position; of the primaries relatively one to the other.

6. The combination as set forth in claim 3, in which the current rectifier is keyed on said common shaft.

7. A combination as set forth in claim 3, in which the angular position of the secondaries windings relatively one to the other and of the primaries windings relatively one to the other is rated to cause the direction of the vector representing, in the excitation circuit, the voltage in load condition of the alternator make a relatively small angle with the direction of the vector representing the no-load voltage for a predetermined value of power factor.

8. A combination as set forth in claim 2, including means to adjust the angular position of the primaries relatively one to the other.

9. A combination as set forth in claim 2, including means to adjust the angular position of the secondaries relatively one to the other.

10. The combination as set forth in claim 5, in which the angular position of the secondary windings relatively one to the other and of the primary windings relatively one to the other is. rated to cause the direction of the vector representing, in the excitation circuit, the voltage in load/condition of the alternator make a relatively small angle with the direction of the vector representing the no-load voltage for a predetermined value of power factor.

11. The combination as set forth in claim 6, in which the common shaft rotates with the shaft of the alternator.

12. The combination as set forth in claim 1, in which the rotary-field.transformers are of the rotary type hav-- References Cited'in the file of this patent UNITED STATES PATENTS 1,936,801 Nycum Nov. 28, 1933 2,195,116 Modlinger Mar. 26, 1940 2,414,287 Crever Jan. 14, 1947 2,722,652 Brainard Nov. 1, 1955. FOREIGN PATENTS.

909,475 Germany Mar. 11', 1954 

